1. Field of the Invention
This invention relates to power-operated clutch control mechanisms for motor vehicles and other power transmission systems, and in particular, this invention relates to electrically actuated manually controlled automobile clutches for persons who are handicapped or are otherwise unable to operate clutches that are controlled by foot pedals in cars having manual transmissions.
2. Description of the Prior Art
Despite the advent and popularity of automatic transmissions, a great many automobiles and trucks presently are constructed with manually operated gear shifts. Cars with manual transmissions enjoy several advantages generally, including increased fuel efficiency and better control of the vehicle. However, such cars must be equipped with independently operated clutches to disengage the engine from the drive shaft while the gears are being shifted. Since this action requires the application of substantial force, a purely mechanical clutch must be actuated by the driver through a foot pedal mechanism. This type of vehicle, although very common, has the disadvantage of being difficult or impossible to operate for drivers who have suffered the impairment or loss of a leg. Such drivers are generally restricted to operation of vehicles with automatic transmissions.
The prior art includes vehicles with manually operated throttles, brakes, and headlight dimmer switches. Manual clutch control systems have been disclosed also that are hydraulically or pneumatically powered, using compressed air, brake-type fluid, or similar working fluids, or connected to the engine manifold vacuum system. These clutches are controlled generally by manual operation of a hydraulic valve or fluid switch, whereby a source of hydraulic power may be connected to a hydraulic cylinder and piston arrangement or other equivalent energy-conversion mechanism which drives the clutch plates. These valves have an on-off character which precludes a gradual engagement or disengagement of the clutch, and the rate of operation of the clutch is not subject to the driver's control, but is determined by the parameters of the hydraulic circuit in these systems. Hence, "feathering" a clutch, gradual engagement of the clutch when starting the vehicle from a standstill, or slipping the clutch while driving under special conditions, is not feasible with such a manual control valve. Therefore, this system can only supplement the conventional pedal clutch control, and it is not satisfactory for a driver who has completely lost the use of his clutch pedal leg.
The prior art also discloses hydraulically or pneumatically actuated manual clutch control systems having a slower or variable rate of clutch engagement to enable such systems to start up the vehicle from a dead stop and to provide better control of the vehicle. One device includes means for constricting the flow of working fluid momentarily at the time when the clutch plates are nearing the point of engagement. Another system provides a dashpot connected to the linkage mechanism which retards the axial motion of the clutch plates at the point of engagement. The dashpot resistance is governed by the engine throttle in such a way that the inhibitory effect is decreased as the throttle is opened, so that the clutch engages more rapidly at greater engine speeds. Although these systems partially overcome the disadvantages discussed above, they do not allow the driver to control independently the rate of clutch engagement, and therefore they provide less control over the vehicle operation in comparison with the conventional pedal-operated clutch control systems. Furthermore these systems contain mechanically complex and expensive components with many moving parts. They are subject to wear and require additional maintenance and adjustment for proper operation. The practical limitations of these systems have therefore precluded their widespread use.
In summary, there is no manual clutch control system presently available which allows handicapped individuals to operate motor vehicles with satisfactory control and which is relatively inexpensive, easy to adjust and maintain, and simple to install in a conventional vehicle.